Description:FIELD OF INVENTION
[0001] The present disclosure relates to bio-electrochemical systems. More specifically, the present disclosure relates to a microbial based electrochemical system and a method for generating bioelectricity from wastewater by utilizing high potent electrogenic microbes to convert organic substrates in the wastewater into electrical energy, simultaneously addressing the challenges of sustainable energy production and wastewater management.
BACKGROUND
[0002] Wastewater treatment is a critical environmental concern due to its potential detrimental effects on human life and ecosystems. The increasing volume of wastewater generated by individuals and industries necessitates efficient and sustainable methods for purification and recycling. Traditional wastewater treatment methods often require significant energy input and may not address the growing need for renewable energy sources.
[0003] Electrochemical platforms have emerged as a promising solution for wastewater treatment and energy generation. The electrochemical platforms utilize microbial activity to break down organic compounds in wastewater while simultaneously producing electricity. However, existing electrochemical platforms face several limitations that hinder their widespread adoption and large-scale implementation.
[0004] One of the primary challenges in existing electrochemical wastewater treatment systems is their limited cost-effectiveness. The high initial investment and operational costs associated with electrochemical platforms often outweigh the benefits of energy generation, making them less attractive for widespread implementation. Additionally, many existing systems suffer from long start-up times, which can delay the treatment process and reduce overall efficiency.
[0005] Another significant limitation of existing electrochemical platforms is the lack of proper optimization. Many systems struggle to achieve consistent performance across varying wastewater compositions and environmental conditions. Such inconsistency can lead to reduced treatment efficiency and lower energy output, limiting the practical applications of these technologies.
[0006] Some existing approaches utilize materials such as conductive material, a polymer, a catalyst, and a mineral to optimize the performance of electrochemical platforms. However, such additional materials add complexity and cost to the system, potentially limiting its scalability and practical implementation. Moreover, the introduction of additional materials may interfere with the natural biofilm formation process or alter the microbial community structure, leading to unpredictable long-term performance. The use of conductive materials, while aiming to enhance electron transfer, can sometimes create unfavorable conditions for microbial growth or attachment. Polymers, intended to improve biofilm stability, may inadvertently create diffusion barriers that hinder substrate access or product removal. Catalysts, though designed to accelerate reactions, can be subject to fouling or poisoning in the complex wastewater environment, reducing their effectiveness over time. Minerals, added to provide trace elements or improve conductivity, may accumulate and cause scaling issues, particularly in long-term operations.
[0007] Microbial desalination cells (MDCs) have been proposed as an alternative approach for wastewater treatment and bioelectricity generation. While MDCs offer some advantages, they also present significant drawbacks. MDCs often require complex setups that are highly expensive compared to other microbial fuel cell technologies. The complexity of MDC can lead to increased maintenance requirements and reduced reliability, limiting their practical application in various settings.
[0008] Therefore, there is a need to overcome the problems discussed above in wastewater treatment while producing bioelectricity.
OBJECTIVES
[0009] The primary objective of the present disclosure is to provide a cost-effective and scalable microbial based electrochemical system for bioelectricity generation from wastewater treatment.
[0010] Another objective of the present disclosure is to utilize high potent electrogenic microbes for enhanced bioelectricity generation.
[0011] Yet another objective of the present disclosure is to enable simultaneous wastewater treatment and bioelectricity generation.
[0012] Yet another objective of the present disclosure is to provide a microbial based electrochemical system that can operate effectively with a wide range of wastewater compositions and organic substrates.
[0013] Yet another objective of the present disclosure is to minimize the start-up time of the microbial based electrochemical system.
[0014] Yet another objective of the present disclosure is to reduce the reliance on additional materials such as polymers, catalysts, or minerals, thereby simplifying the system design and reducing costs.
[0015] Yet another objective of the present disclosure is to contribute to sustainable development by offering an environmentally friendly solution for both wastewater treatment and renewable energy generation.
[0016] Still another objective of the present disclosure is to provide a method for isolating and depositing high potent electrogenic microbes on electrodes.
SUMMARY
[0017] The present disclosure addresses the limitations of existing approaches and provides a technical solution for simultaneous wastewater treatment and bioelectricity generation through an optimized microbial-based electrochemical system. The present disclosure overcomes limitations of existing approaches by incorporating a method of isolating and testing high potent electrogenic microbes from wastewater before utilizing for bioelectricity generation, thereby enhancing overall performance and efficiency. Deposition of the high potent electrogenic microbes directly on an anode electrode of a dual chamber system significantly reduces the start-up time of the microbial-based electrochemical system and enables to achieve operational status more rapidly. The high potent electrogenic microbes are capable of initiating efficient electron transfer processes almost immediately upon introduction to the system. The rapid start-up capability is particularly beneficial in practical applications where quick deployment and operation are crucial. The reduced start-up time not only enhances the overall efficiency of the system but also makes it more adaptable to varying wastewater inflows and changing operational demands. Further, the system eliminates the need for additional materials such as polymers or catalysts, simplifying the system design and reducing costs. In addition, the anode electrode of the system is a glassy carbon electrode that provides a greater surface area, improves a better microbial attachment, and is highly conductive, while the cathode electrode is a silver chloride electrode. Also, the microbial based electrochemical device is a handheld device, making it highly portable and suitable for on-site applications.
According to one aspect of the present disclosure, a method of generating a microbial based electrochemical device for producing bioelectricity is provided. The method comprises steps of: forming a dual chamber comprising an anode chamber and a cathode chamber; adding wastewater as an organic substrate in the anode chamber; adding electrolytic buffer in the cathode chamber; immersing an anode electrode in the wastewater and a cathode electrode in the electrolytic buffer, wherein the anode electrode and cathode electrode are immersed in the anode chamber and cathode chamber, respectively, either before or after addition of the wastewater and electrolytic buffer; identifying high potent electrogenic microbes from a wastewater stream source; depositing the high potent electrogenic microbes on the anode electrode prior to immersing in the wastewater; generating electrons and protons by the high potent electrogenic microbes through microbial oxidation of the organic substrate; and transferring the electrons and protons from the anode chamber to the cathode chamber to generate bioelectricity. The anode electrode is a glassy carbon electrode. The cathode electrode is silver (Ag) or silver chloride (AgCl) electrode. The electrolytic buffer is tris(hydroxymethyl)aminomethane (TRIS) buffer or potassium ferricyanide buffer. The anode chamber is an anaerobic chamber.
[0018] The method further comprises a step of isolating the high potent electrogenic by isolating electrogenic microbes from wastewater stream; washing bacterial pellet twice with phosphate-buffered saline (PBS); suspending washed pellet in PBS; testing resulting suspension containing the electrogenic bacterial pellet, using a cyclic voltammetry within a potential range of 0 to -0.7 Volts (V) for 7 cycles at a scan rate of 0.05 Volts per second (V/s); and selecting electrogenic microbes exhibiting high current generation as the high potent electrogenic microbes.
[0019] The method further comprises a step of isolating the high potent electrogenic by isolating electrogenic microbes from wastewater stream; washing electrogenic fungal pellet twice with phosphate-buffered saline (PBS); suspending washed fungal pellet in potato dextrose broth (PDB); testing resulting suspension containing the electrogenic fungal pellet using a cyclic voltammetry within a potential range of 0 to -0.45 V for 7 cycles at a scan rate of 0.1 Volts per second (V/s); and selecting electrogenic microbes exhibiting high current generation as the high potent electrogenic microbes. The high potent electrogenic microbes are capable of generating a current of at least 0.23 milliampere (mA) per 100 microliter (μl) of microbial suspension with 10^6 cell density.
[0020] The method further comprises the steps of: positioning a separator positioned between the anode chamber and the cathode chamber for allowing transfer of protons from the anode chamber to the cathode chamber; and positioning an external circuit between the anode chamber and the cathode chamber for allowing transfer of electrons from the anode chamber to the cathode chamber.
[0021] According to another aspect of the present disclosure, a microbial based electrochemical system for generating bioelectricity from wastewater is provided. The system comprises a microbial based electrochemical device that comprises a dual chamber comprising an anode chamber and a cathode chamber. The anode chamber comprises wastewater as an organic substrate; and an anode electrode immersed in the wastewater. The anode electrode is deposited with high potent electrogenic microbes. The cathode chamber comprises an electrolytic buffer; and a cathode electrode immersed in the electrolytic buffer. The electrogenic microbes generate electrons and protons through microbial oxidation of the organic substrate. The electrons and protons generated in the anode chamber are transferred to the cathode chamber to generate bioelectricity. The high potent electrogenic microbes are capable of generating a current of at least 0.23 milliampere (mA) per 100 microliter (μl) of microbial suspension with 10^6 cell density. The anode electrode is a glassy carbon electrode; and the cathode electrode is silver (Ag) or silver chloride (AgCl) electrode. The electrolytic buffer is tris(hydroxymethyl)aminomethane (TRIS) buffer or potassium ferricyanide buffer. The anode chamber is an anaerobic chamber.
[0022] The high-potent electrogenic microbes are isolated by isolating microbes from wastewater stream; washing bacterial pellet twice with phosphate-buffered saline (PBS); suspending washed pellet in PBS; and testing resulting suspension containing the bacterial pellet, using a cyclic voltammetry within a potential range of 0 to -0.7 Volts (V) for 7 cycles at a scan rate of 0.05 Volts per second (V/s).
[0023] The high-potent electrogenic microbes are isolated by isolating microbes from wastewater stream; washing fungal pellet twice with phosphate-buffered saline (PBS); suspending washed fungal pellet in potato dextrose broth (PDB), and testing resulting suspension containing the fungal pellet using a cyclic voltammetry within a potential range of 0 to -0.45 V for 7 cycles at a scan rate of 0.1 Volts per second (V/s).
[0024] The device further comprises a separator positioned between the anode chamber and the cathode chamber for allowing transfer of protons from the anode chamber to the cathode chamber; and an external circuit positioned between the anode chamber and the cathode chamber for allowing transfer of electrons from the anode chamber to the cathode chamber.
[0025] The foregoing paragraphs have been provided by way of general introduction and are not intended to limit the scope of the following claims. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 is a block diagram illustrating a microbial based electrochemical system for generating bioelectricity from wastewater in accordance with the present disclosure.
[0027] FIGS. 2 and 3 are graphical representations illustrating an electric current response of isolated electrogenic microbes in accordance with the present disclosure.
[0028] FIGS. 4A and 4B are flow charts illustrating a method of generating a microbial based electrochemical device for producing bioelectricity in wastewater in accordance with the present disclosure.
DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE
[0029] Aspects of the present invention are best understood by reference to the description set forth herein. All the aspects described herein will be better appreciated and understood when considered in conjunction with the following descriptions. It should be understood, however, that the following descriptions, while indicating preferred aspects and numerous specific details thereof, are given by way of illustration only and should not be treated as limitations. Changes and modifications may be made within the scope herein without departing from the spirit and scope thereof, and the present invention herein includes all such modifications.
[0030] As mentioned above, there is a need for a technical solution to solve aforementioned technical problems in wastewater treatment while producing bioelectricity. The present disclosure addresses limitations of existing approaches by introducing a method for isolating and testing high-potent electrogenic microbes from wastewater. The high-potent electrogenic microbes, when deposited directly onto an anode electrode in a dual-chamber system, significantly reduce start-up time and enhance operational efficiency. This approach enables rapid initiation of electron transfer processes, crucial for quick deployment in practical applications. The system's configuration eliminates the need for additional materials like polymers or catalysts, simplifying construction and reducing costs. The glassy carbon anode electrode provides an increased surface area for improved microbial attachment and conductivity, while the silver chloride cathode electrode completes the efficient electrochemical setup. Accordingly, the system of the present disclosure results in a more adaptable, cost-effective, and effectively perform simultaneous wastewater treatment and bioelectricity generation. Also, the microbial based electrochemical device is a handheld device, making it highly portable and suitable for on-site applications.
[0031] Referring now to the drawings, and more particularly to FIGS. 1 through 4B, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments.
[0032] FIG. 1 is a block diagram illustrating a microbial based electrochemical system 100 for generating bioelectricity from wastewater in accordance with the present disclosure. The system 100 comprises a microbial based electrochemical device 102 that generates bioelectricity from wastewater. The microbial based electrochemical device 102 comprises a dual chamber comprising an anode chamber 104 and a cathode chamber 106. It is to be noted that the microbial based electrochemical device 102 refers to a bio electrochemical system that harnesses the metabolic activities of electrogenic microorganisms to generate electrical current while treating wastewater.
[0033] The anode chamber 104 comprises wastewater as an organic substrate and an anode electrode 108 immersed in the wastewater. The wastewater is an anolyte. The wastewater refers to liquid waste generated from various domestic, industrial, commercial, and agricultural activities. The wastewater serves as the organic substrate in the anode chamber 104 of the device 102. The diverse organic compounds present in the wastewater act as electron donors for electrogenic microbes, which oxidize the substances during their metabolic processes. The oxidation process generates electrons and protons, driving the bioelectricity generation process while simultaneously reducing the organic load of the wastewater, effectively treating the wastewater. Prior to utilization, the wastewater is analyzed for key parameters including pH, total dissolved solids (TDS), salinity, and electrical conductivity (EC). Optimization of wastewater parameters is carried out through a series of controlled experiments to ensure optimal performance of electrogenic microbes (microgens) within the electrochemical device. pH is adjusted using buffering agents or mild acids/bases across a range (typically 5.5–7.5) to determine the level at which microbial activity and bioelectricity generation are maximized. TDS is controlled by diluting the wastewater or applying pre-treatment methods to avoid osmotic stress or ion toxicity that can hinder microbial performance. Salinity is optimized by varying salt concentrations and selecting levels that maintain microbial viability without inhibiting electron transfer, especially for halotolerant strains. EC is regulated by adjusting electrolyte concentrations to balance ionic strength and internal resistance, thereby improving current output. Throughout this process, bioelectricity generation (voltage/current), microbial growth, and organic load reduction are monitored to identify the effective parameter range.
[0034] The anode chamber 104 is an anaerobic chamber. The anaerobic environment provided in the anode chamber 104 creates optimal conditions for electrogenic microbes and forces them to transfer electrons to the anode electrode 108 rather than to oxygen, thereby enhancing electricity generation efficiency. The anaerobic conditions prevent competing reactions with oxygen, maintain a significant redox potential difference between the anode chamber 104 and the cathode chamber 106, and create a selective pressure favoring electrogenic microbes. The anaerobic environment also enhances substrate utilization through anaerobic processes like fermentation, which can break down complex organic compounds in wastewater more efficiently. Furthermore, the anaerobic environment mimics the natural habitats of many electrogenic microbes found in anaerobic environments like lake sediments or animal guts. By providing the anaerobic conditions, the microbial fuel cell system 100 maximizes bioelectricity generation efficiency while effectively treating wastewater through microbial metabolic processes.
[0035] High-potent electrogenic microbes, which are isolated from wastewater and tested for efficiency, are deposited onto the surface of the anode electrode 108. The anode electrode 108 functions as an electron acceptor for the metabolic processes of the electrogenic microbes, collecting the electrons generated during the oxidation of organic compounds in the wastewater. It is to be noted that any deposition technique can be used for depositing the high-potent electrogenic microbes on the anode electrode 108. For instance, the deposition technique may include direct inoculation, electrodeposition, spray coating, and dip coating. The electrogenic microbes refer to microorganisms capable of generating and transferring electrons outside their cell membranes. The high-potent electrogenic microbes demonstrate superior ability to generate and transfer electrons outside their cell membranes during the oxidation of organic compounds in wastewater. The high potent electrogenic microbes are capable of generating a current of at least 0.23 milliampere (mA) per 100 microliter (μl) of microbial suspension with 10^6 cell density. The deposited electrogenic microbes form biofilm. The biofilm enables firm microbial adhesion to the anode electrode 108, increases the effective surface area for microbial activity, enhances electron transfer, protects microbes from potential toxins, allows for synergistic interactions among different species, improves substrate accessibility, and maintains long-term electrochemical activity through self-regeneration.
[0036] In some embodiments, for isolating microbes, wastewater is collected from any resource. After collecting the wastewater, physicochemical characteristics of the wastewater are determined. The physicochemical characteristics of wastewater may include, but are not limited to, pH, temperature, electrical conductivity (EC), total dissolved solids (TDS), chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS), dissolved oxygen (DO), oxidation-reduction potential (ORP), turbidity, nitrogen content, phosphorus content, heavy metal concentrations, sulfate content. For the isolation of microbes from wastewater, the pH of the media, that was used for the isolation of microbes, was kept neutral, that is., 6.9±7.5. However, the wastewater is just a source (environmental sample) from which the microbes are isolated, which varied in the pH, thus for proper isolation of microbes, the pH was kept more about neutral.
[0037] Then, the serial dilution of wastewater is performed. Plating of 100 µL of aliquots from 10-6, 10-5,10-4 dilutions is performed on nutrient agar plates and potato dextrose agar plates and incubated plates for colony formation. After colony formation, distinct colonies are selected based on morphological characteristics. Morphological characteristics include, but not limited to, colony color, colony texture, colony margin, colony shape, color of colony from a backside of a culture plate, elevation of the colony, and form of the colony.
[0038] The purification of isolated microbial strains involves a series of steps to ensure pure cultures for use in the microbial-based electrochemical system. The individual colonies are streaked onto fresh agar plates using the streak plate technique, repeated 3-4 times to separate mixed cultures. The single colonies are then selected and transferred to new plates. Microscopic examination, including gram staining, confirms culture purity and cell morphology. Pure colonies are inoculated into liquid media, grown, and then centrifuged, resulting in bacterial pellets and/or fungal pellets. All these strains are then tested for electricity generation using a potentiostat or a cyclic voltammetry (CV). Cyclic voltammetry is an electrochemical technique used to study the redox behavior of chemical species. It involves applying a varying electrical potential to an electrode and measuring the resulting current.
[0039] The high-potent electrogenic microbes are isolated by washing bacterial pellet twice with phosphate-buffered saline (PBS); suspending washed pellet in PBS; depositing the resulting suspension containing the electrogenic bacterial pellet on a carbon based screen printed electrode, and testing the sample, using the cyclic voltammetry within a potential range of 0 to -0.7 Volts (V) for 7 cycles at a scan rate of 0.05 Volts per second (V/s).
[0040] The high-potent electrogenic microbes are isolated by washing fungal pellet twice with phosphate-buffered saline (PBS); suspending washed fungal pellet in potato dextrose broth (PDB), depositing the resulting suspension containing the electrogenic bacterial pellet on the carbon based screen printed electrode, and testing resulting suspension containing the fungal pellet using a cyclic voltammetry within a potential range of 0 to -0.45 V for 7 cycles at a scan rate of 0.1 Volts per second (V/s).
[0041] The cell density is maintained constant (106) for all cyclic voltammetry analysis. The results from the cyclic voltammetry analysis graphs (seen in .g., in FIGS. 2 and 3) represented that three bacterial strains coded as B(I)5.2; J(O)4.1, and J(I)5.2 represented a change in the peak pattern during oxidation phase, while in case of fungi, V5(iii), B(I)4(i), B(I)5(ii) showed a positive current response. FIG. 2 illustrates a graphical representation of current response measured for various bacterial strains subjected to cyclic voltammetry analysis under specific experimental conditions. FIG. 3 illustrates a graphical representation of current response measured for various fungal strains subjected to cyclic voltammetry analysis under specific experimental conditions. The graphical representation illustrates the relationship between the current response (mA) and the applied potential (V) within a defined range. Thus, based on the above discussed parameters, the highest potent bacterial strain is B(I)5.2 with a current generation of 0.02mA, while in case of fungi, the highest potent strain is V5(iii), that showed 0.032 mA of the current response. The highest potent strain V5(iii) showed the highest similarity with Aspergillus flavus.
[0042] In some embodiments, the high potent electrogenic microbes include gram-positive bacteria, oxidase positive bacteria, catalase positive bacteria, Aspergillus spp., or combinations thereof.
[0043] In some embodiments, in the fabrication of the dual-chamber microbial fuel cell (DC-MFC), various configurations of electrogenic microbes are explored to optimize current generation. The process involves depositing different combinations of microorganisms onto the anode electrode 108, including: (i) individual bacterial strains, (ii) individual fungal strains, (iii) combinations of multiple bacterial strains, (iv) combinations of multiple fungal strains, and (v) mixed consortia of both bacteria and fungi. The diverse microbial configurations may demonstrate the highest current output. The flexibility to combine bacteria and fungi in the deposition process provides an opportunity to harness the unique metabolic capabilities of both prokaryotic and eukaryotic microorganisms, potentially leading to more robust and efficient bioelectricity generation from diverse wastewater streams.
[0044] The anode electrode 108 is a glassy carbon electrode. The glassy carbon electrode offers high electrical conductivity for efficient electron transfer, a large surface area for microbial attachment and biofilm formation, and biocompatibility that supports sustained microbial activity. Glassy carbon's chemical stability ensures long-term durability in diverse wastewater environments, while its low background current allows accurate measurement of bio electrochemical activity. The glassy carbon electrode’s surface may be easily modified to enhance microbial adhesion or electron transfer if needed. The glassy carbon electrode’s mechanical strength makes it robust for anode chamber conditions, and its ease of cleaning contributes to the system's cost-effectiveness. Accordingly, the glassy carbon electrode enhances the overall efficiency of bioelectricity generation from wastewater in the microbial-based electrochemical system 100. In some embodiments, the anode electrode 108 is a cylindrical electrode.
[0045] The cathode chamber 106 comprises an electrolytic buffer; and a cathode electrode 110 immersed in the electrolytic buffer. The electrolytic buffer is a catholyte. In some embodiments, the cathode electrode 110 is silver (Ag) or silver chloride (AgCl) electrode. In some embodiments, the cathode electrode 110 is a cylindrical electrode. The cathode electrode 110 functions as final electron acceptor in the system 100, where electrons transferred from the anode electrode 108 combine with protons and oxygen to form water. The silver or silver chloride composition provides high conductivity and a suitable reduction potential, enhancing the overall efficiency of the bioelectricity generation process. Additionally, the silver-based cathode exhibits antimicrobial properties that help prevent biofouling, ensuring stable long-term performance of the system 100. The electrogenic microbes generate electrons and protons through microbial oxidation of the organic substrate. The electrons and protons generated in the anode chamber 104 are transferred to the cathode chamber 106 to generate bioelectricity. The electrolytic buffer is tris(hydroxymethyl)aminomethane (TRIS) buffer or potassium ferricyanide buffer.
[0046] Further, the use of cylindrical anode and cathode electrodes in the microbial-based electrochemical system 100 offers numerous advantages such as increased surface area for microbial attachment and reactions, improved mass transfer and fluid dynamics, more uniform current distribution, enhanced scalability, and better structural integrity. Cylindrical electrodes promote better diffusion of substrates and products, create beneficial turbulence patterns in flowing systems, and are easily scalable to match different reactor volumes or power requirements.
[0047] The device 102 further includes a separator 112 positioned between the anode chamber 104 and the cathode chamber 106 for allowing transfer of protons from the anode chamber 104 to the cathode chamber 106. The separator 112 may be a slat bridge or a separating membrane. In salt bridge configuration, the separator 112 consists of a tube filled with a concentrated electrolyte solution, often potassium chloride or sodium chloride. The salt bridge allows selective movement of ions between the anode chamber 104 and the cathode chamber 106 while preventing the mixing of the anolyte and catholyte. In separating membrane configuration, materials include Nafion™, a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer, or other proton exchange membranes are used. The separating membranes are selectively permeable to protons while blocking the passage of larger molecules and maintaining electrical insulation between the anode chamber 104 and the cathode chamber 106. The separator 112 allows protons generated in the anode chamber 104 to migrate to the cathode chamber 106, maintaining charge balance. The separator 112 further prevents oxygen diffusion from the cathode chamber 106 to the anode chamber 104, preserving the anaerobic conditions necessary for the electrogenic microbes. 3. It helps maintain the chemical gradient between the two chambers, which is essential for the overall electrochemical process. The choice between the salt bridge and the separating membrane depends on factors such as the specific wastewater composition, desired system efficiency, and operational requirements.
[0048] The device 102 further comprises an external circuit 114 positioned between the anode chamber 104 and the cathode chamber 106 for allowing transfer of electrons from the anode chamber 104 to the cathode chamber 106. The external circuit 114 consists of conductive wires connecting the anode electrode 108 to the cathode electrode 110.
[0049] In some embodiments, the device 102 is a portable microbial based electrochemical device. The portable design allows for easy transportation and deployment of the device in various locations, making it suitable for on-site wastewater treatment and bioelectricity generation in diverse settings.
[0050] In some embodiments, the device 102 may include variations in chamber design, electrode materials, microbial strains, and operational conditions. Additionally, the anode chamber 104 may integrate wastewater effluents from different sources to optimize substrate availability, while the cathode chamber 104 might utilize alternative buffers to improve reduction reactions. The modifications aim to increase scalability and efficiency, making the microbial fuel cell adaptable to diverse wastewater treatment and energy generation applications.
[0051] With reference to FIGS 1-3, FIGS. 4A and 4B are flow charts illustrating a method of generating a microbial based electrochemical device for producing bioelectricity in wastewater in accordance with the present disclosure. At step 402, the method includes forming a dual chamber comprising the anode chamber 104 and the cathode chamber 106. The anode chamber 104 comprises the anode electrode 108. The cathode chamber 106 comprises the cathode electrode 110. In some embodiments, the anode chamber 104 and the cathode chamber 106 are fabricated using glass material. It is to be noted that the material for fabricating the anode chamber 104 and the cathode chamber 106 is flexible and can be tailored to specific needs. Similarly, the volumes of the anode chamber 104 and the cathode chamber 106 can be customized to meet particular operational requirements. Further, the anode electrode 108 is a glassy carbon electrode. The cathode electrode 110 is a silver (Ag) or silver chloride (AgCl) electrode. It is to be noted that the techniques known in the prior art are used to manufacture the anode electrode 108 and the cathode electrode 110.
[0052] At step 404, the method includes adding wastewater as an organic substrate in the anode chamber 104. The wastewater from any source is added. The anode chamber 104 is the anaerobic chamber. In some embodiments, prior to addition, the wastewater is analyzed for its physicochemical properties such as pH, conductivity, chemical oxygen demand (COD), and total organic carbon (TOC) to ensure compatibility with the system 100. Depending on the source, the wastewater may undergo pre-treatment steps such as filtration or pH adjustment to optimize conditions for microbial activity. The amount of wastewater added is measured to maintain an appropriate organic loading rate and hydraulic retention time within the anode chamber. Methods to ensure and maintain anaerobic conditions are implemented, such as nitrogen purging or the use of oxygen scavengers. The wastewater may be brought to an optimal temperature range (typically 25-35°C) to promote microbial activity. If necessary, the wastewater may be supplemented with wastewater effluents and trace nutrients to support microbial growth and metabolism.
[0053] At step 406, the method includes adding electrolytic buffer in the cathode chamber 106. The electrolytic buffer is tris(hydroxymethyl)aminomethane (TRIS) buffer or potassium ferricyanide buffer. The volume and concentration of the buffer are optimized based on the cathode chamber size and the expected electron flow. The buffer is added in a manner that ensures complete immersion of the cathode electrode 110 while avoiding air pockets.
[0054] At step 408, the method includes immersing the anode electrode 108 in the wastewater. The anode electrode 108 is positioned within the anode chamber 104 to maximize contact with the wastewater, ensuring optimal performance. The depth and orientation of immersion are precisely controlled to optimize surface area exposure and fluid dynamics while maintaining necessary connections above the liquid level. Prior to immersion, the anode electrode 108 may undergo pre-treatment or conditioning.
[0055] At step 410, the method includes immersing the cathode electrode 110 in the electrolytic buffer. The cathode electrode 110 is positioned within the cathode chamber 106 to ensure optimal contact with the electrolytic buffer. The immersion depth is controlled to maximize the electrode's active surface area while maintaining any necessary connections above the liquid level. The orientation of the cylindrical electrode may be optimized to promote efficient oxygen reduction reactions at the cathode surface. The positioning of the cathode electrode relative to the separator 112 (membrane or salt bridge) is considered to minimize internal resistance. It is to be noted that steps 408 and 410 are interchangeable in sequence and may be executed in any order without affecting the outcome.
[0056] At step 412, the method includes identifying high potent electrogenic microbes from a wastewater stream source. The high-potent electrogenic microbes are isolated by washing bacterial pellet twice with phosphate-buffered saline (PBS); suspending washed pellet in PBS; depositing the resulting suspension containing the electrogenic bacterial pellet on a carbon based screen printed electrode, and testing the sample, using the cyclic voltammetry within a potential range of 0 to -0.7 Volts (V) for 7 cycles at a scan rate of 0.05 Volts per second (V/s). The high-potent electrogenic microbes are isolated by washing fungal pellet twice with phosphate-buffered saline (PBS); suspending washed fungal pellet in potato dextrose broth (PDB), depositing the resulting suspension containing the electrogenic bacterial pellet on the carbon based screen printed electrode, and testing resulting suspension containing the fungal pellet using a cyclic voltammetry within a potential range of 0 to -0.45 V for 7 cycles at a scan rate of 0.1 Volts per second (V/s).
[0057] At step 414, the method includes depositing high potent electrogenic microbes on the anode electrode 108. The microbes, either as single strains or consortia of bacteria and/or fungi, are prepared through cultivation methods. The deposition technique, such as direct inoculation, electrodeposition, or dip coating, is selected to ensure uniform distribution and optimal coverage of the anode electrode 108. An amount of microbial suspension is applied may vary depending on several factors, including electrode surface area, microbial cell density, microbial characteristics, desired initial biofilm thickness, system scale, wastewater composition, and chosen deposition technique. The operating conditions such as temperature, pH, and anaerobic environment are controlled during the process.
[0058] At step 416, the method includes generating electrons and protons by the high potent electrogenic microbes through microbial oxidation of the organic substrate. The electrogenic microbes, established as a biofilm on the anode electrode 108, metabolize organic compounds from the wastewater. Through intracellular oxidation, the microbes break down the organic compounds, releasing electrons that are transferred to the anode electrode 108 via various mechanisms and protons that are released into the anode chamber 104. It simultaneously achieves wastewater treatment by breaking down organic pollutants and facilitates bioelectricity generation through electron flow and proton migration.
[0059] At step 418, the method includes transferring the electrons and protons from the anode chamber 104 to the cathode chamber 106 to generate bioelectricity. The electrons generated by the microbial oxidation in the anode chamber 104 are transferred to the cathode chamber 106 through external circuit 114. The flow of electrons constitutes an electrical current, which can be harnessed as bioelectricity. Simultaneously, the protons produced in the anode chamber 104 migrate through the separator 112 (proton exchange membrane or salt bridge) to the cathode chamber 106. The proton movement is essential for maintaining charge balance in the system 100. The amount of energy generation could be identified by attaching a digital multimeter. The bioenergy can then later be utilized to provide energy for operating smaller devices.
[0060] Accordingly, the system and method of the present disclosure simultaneously address the challenges of wastewater treatment and sustainable energy production. By harnessing the metabolic capabilities of high-potent electrogenic microbes, the system effectively converts organic pollutants in wastewater into bioelectricity. By incorporating a dual-chamber configuration with specialized electrodes and a method for isolating and depositing electrogenic microbes, overcomes limitations of traditional systems, such as long start-up times and the need for additional catalysts. This technology not only contributes to environmental sustainability by treating wastewater but also offers a promising source of renewable energy. The adaptability and scalability of the system make it suitable for various applications, from small-scale decentralized units to larger industrial implementations.
[0061] The embodiments of the present invention disclosed herein are intended to be illustrative and not limiting. Other embodiments are possible and modifications may be made to the embodiments without departing from the spirit and scope of the invention. As such, these embodiments are only illustrative of the inventive concepts contained herein.
, Claims:1. A method of generating a microbial based electrochemical device (102) for producing bioelectricity in wastewater, comprising steps of:
forming a dual chamber comprising an anode chamber (104) and a cathode chamber (106);
adding wastewater as an organic substrate in the anode chamber (104);
adding electrolytic buffer in the cathode chamber (106);
immersing an anode electrode (108) in the wastewater and a cathode electrode (110) in the electrolytic buffer, wherein the anode electrode (108) and cathode electrode (110) are immersed in the anode chamber (104) and cathode chamber (106), respectively, either before or after addition of the wastewater and electrolytic buffer;
identifying high potent electrogenic microbes from a wastewater stream source;
depositing the high potent electrogenic microbes on the anode electrode (108) prior to immersing in the wastewater;
generating electrons and protons by the high potent electrogenic microbes through microbial oxidation of the organic substrate; and
transferring the electrons and protons from the anode chamber (104) to the cathode chamber (106) to generate bioelectricity.
2. The method as claimed in claim 1, wherein identifying high potent electrogenic microbes from a wastewater stream source comprises steps of:
isolating microbes from the wastewater stream source;
washing bacterial pellet twice with phosphate-buffered saline (PBS);
suspending washed pellet in PBS;
testing resulting suspension containing the bacterial pellet, using a cyclic voltammetry within a potential range of 0 to -0.7 Volts (V) for 7 cycles at a scan rate of 0.05 Volts per second (V/s); and
selecting electrogenic microbes exhibiting high current generation as the high potent electrogenic microbes.
3. The method as claimed in claim 1, wherein identifying high potent electrogenic microbes from a wastewater stream source comprises steps of:
isolating microbes from the wastewater stream source;
washing fungal pellet twice with phosphate-buffered saline (PBS);
suspending washed fungal pellet in potato dextrose broth (PDB);
testing resulting suspension containing the fungal pellet using a cyclic voltammetry within a potential range of 0 to -0.45 V for 7 cycles at a scan rate of 0.1 Volts per second (V/s); and
selecting electrogenic microbes exhibiting high current generation as the high potent electrogenic microbes.
4. The method as claimed in claim 1, wherein the high potent electrogenic microbes are capable of generating a current of at least 0.23 milliampere (mA) per 100 microliter (μl) of microbial suspension with 10^6 cell density.
5. The method as claimed in claim 1, wherein the anode electrode (108) is a glassy carbon electrode.
6. The method as claimed in claim 1, wherein the cathode electrode (110) is silver (Ag) or silver chloride (AgCl) electrode.
7. The method as claimed in claim 1, wherein the electrolytic buffer is tris(hydroxymethyl)aminomethane (TRIS) buffer or potassium ferricyanide buffer.
8. The method as claimed in claim 1, wherein the anode chamber (104) is an anaerobic chamber.
9. The method as claimed in claim 1, further comprising the steps of:
positioning a separator (112) positioned between the anode chamber (104) and the cathode chamber (106) for allowing transfer of protons from the anode chamber (104) to the cathode chamber (106); and
positioning an external circuit (114) between the anode chamber (104) and the cathode chamber (106) for allowing transfer of electrons from the anode chamber (104) to the cathode chamber (106).
10. A microbial based electrochemical system (100) for generating bioelectricity from wastewater, comprising:
a microbial based electrochemical device (102) that comprises
a dual chamber comprising:
an anode chamber (104) comprising:
wastewater as an organic substrate; and
an anode electrode (108) immersed in the wastewater, wherein the anode electrode (108) is deposited with high potent electrogenic microbes;
a cathode chamber (106) comprising:
an electrolytic buffer; and
a cathode electrode (110) immersed in the electrolytic buffer; and
wherein the electrogenic microbes generates electrons and protons through microbial oxidation of the organic substrate; and the electrons and protons in the anode chamber (104) are transferred to the cathode chamber (106) to generate bioelectricity.
11. The system (100) as claimed in claim 10, wherein the high potent electrogenic microbes are capable of generating a current of at least 0.23 milliampere (mA) per 100 microliter (μl) of microbial suspension with 10^6 cell density.
12. The system (100) as claimed in claim 10, wherein the high-potent electrogenic microbes are isolated by isolating microbes from a wastewater stream source; washing bacterial pellet twice with phosphate-buffered saline (PBS); suspending washed pellet in PBS; testing resulting suspension containing the bacterial pellet, using a cyclic voltammetry within a potential range of 0 to -0.7 Volts (V) for 7 cycles at a scan rate of 0.05 Volts per second (V/s); and selecting electrogenic microbes exhibiting high current generation as the high potent electrogenic microbes.
13. The system (100) as claimed in claim 10, wherein the high-potent electrogenic microbes are isolated by isolating microbes from wastewater stream; washing fungal pellet twice with phosphate-buffered saline (PBS); suspending washed fungal pellet in potato dextrose broth (PDB), testing resulting suspension containing the fungal pellet using a cyclic voltammetry within a potential range of 0 to -0.45 V for 7 cycles at a scan rate of 0.1 Volts per second (V/s); and selecting electrogenic microbes exhibiting high current generation as the high potent electrogenic microbes.
14. The system (100) as claimed in claim 1, further comprising:
a separator (112) positioned between the anode chamber (104) and the cathode chamber (106) for allowing transfer of protons from the anode chamber (104) to the cathode chamber (106); and
an external circuit (114) positioned between the anode chamber (104) and the cathode chamber (106) for allowing transfer of electrons from the anode chamber (104) to the cathode chamber (106).
15. The system (100) as claimed in claim 10, wherein the anode electrode (108) is a glassy carbon electrode; and the cathode electrode (110) is silver (Ag) or silver chloride (AgCl) electrode.
16. The system (100) as claimed in claim 1, wherein the electrolytic buffer is tris(hydroxymethyl)aminomethane (TRIS) buffer or potassium ferricyanide buffer.
17. The system (100) as claimed in claim 1, wherein the anode chamber (104) is an anaerobic chamber.
18. The system (100) as claimed in claim 1, wherein the microbial based electrochemical device (102) is a handheld device.